Spray-gun



R, W. TRACY i May 15, 1934.

SPRAY GUN Filed April 14 1930 wm n N .REN

Patented May 15, 1934 UNTED STATES SPRAY-GUN Robert W. Tracy, Toledo,Ohio, assigner to The De Vilbiss Company, Toledo, Ohio, a corporation ofOhio Application April 14, 1930, Serial No. 443,945'

Claims.

This invention relates to apparatus of the type adapted for applyingpaints, lacquers, or other materials by air pressure to surfaces to becoated, and has particular reference'to the guns 3 used in connectionwith such apparatus.

In the spraying of brushing dopes and other materials of a more viscousnature than ordinary surface coating materials, it is desirous todischarge the atomizing air from the gun both El@ interiorl'y andexteriorly of the discharging material stream so as to effect a morethorough breaking up and atomization of the material than is possiblewhere the air is discharged only in enveloping relation thereto. Thishas here- 35 tofore been accomplished by making the customary controlneedle hollow and directing air therethrough into the center of thematerial stream. In all of such uses of which I am aware, the hollowneedle' valve is the center go conduit of the gun and its discharge endis therefore shifted axially with respect to the material and outer airdischarge orices during any movement of the needle valve in an operationof the gun, which feature has certain objections.

The primary object of my invention is the provision of a gun of thischaracter in which the discharge of at least a portion of the atomizingair is centrally through the control valve but wherein the discharge endof such central air passage remains constant or fixed with respect tothe material 'and outer air discharge' orifices of the gun and, is notvaried by controlling movements of the valve. i

Other objects and advantages of the invention will be apparent from thefollowing detailed description thereof.

While in its broader aspect the invention is capable of embodiment innumerous forms, one

embodiment thereof is illustrated in the accompanying drawing, in which-Figure 1 is a fragmentary side elevation of a spray gun embodying theinvention with a part Yin central longitudinal section and with thecontrol parts in inoperative position, and Fig. 2 is 4| a cross-sectionon the line 2-2 in Fig. l.

Referring to the drawing, 1 ldesignates the gun body having thecustomary handle portion 2 and provided at its discharge end with aspray head 3 of any suitable form, many types of such spray heads beingin use.

The spray head illustrated comprises the inner material dischargenozzle- 4 which is threaded into the forward end of the gun body withits passageway 5 in communication with I8 the material supply passageway6 of the gunl body. An outer air nozzle 'I is mounted in concentricspaced surrounding relation to the outer end portion of the materialdischarge nozzle 4 and has a portion held seated against an annularflange 8 of the nozzle 4 by a union nut 9 en- 60 gaged to the forwardend of the gun body in any convenient or suitable manner. The nozzles 4and 7 cooperate to form an air space 10 therebetween which terminates atits forward end in an annular air discharge orifice 11 in concentric 65relation to the material discharge orifice 12 of the Ainner nozzle 4.The nozzle 7 is of the supplemental air discharge type having thesupplemental air discharge passages 13 in communication with the airsupply space 10. This feature of the nozzle has nothing, however, to dowith the invention.

'Ihe gun body 1 is provided at its rear end substantially in axialalignment with the discharge orifice-of the spray head with a bore oropening 14, the rear end of which is closed by a plug 15 shown in thepresent instance as being threaded therein and its forward end beingopen, except as hereinafter described, to the transverse opening 16 ofthe gun body. A tube 'so l-'l'is carried at its rear end by the plug 15and projects forwardly therefrom through the open- 'ings 14 and 16 andan opening 18 in the forward end portion of the stock, and axiallythrough the center of the material discharge nozzle 4, terminatingsubstantially at the outer end of the discharge orice of such nozzle, orin any desir'ed predetermined relation thereto. The tube 17 isconcentrically spaced laterally from the wall of the nozzle passage 5and its orifice 12 to 90 permit the .passage of A nnadierial through thenozzle around the tube.

The control valve for the material discharge orifice 12 constitutes vatube 19, whichis sleeved on the air tube 17 for movements axiallythereof 9 5 and has its forward end projecting through the. opening 18and into and through the material nozzle 4. The tube 19, which may bereferred to as a sleeve valve", is spaced from the wall of the nozzlepassage 5 to permit the passage of 100 material therethrough, but hasits outer endl adapted to project through the material discharge orifice12, and when at the limit of its outward movement therein to seat insuch orifice to effectually close the same. When the valve 105 sleeve isretracted from its forward position shown in the drawing, it effects anopening of the oriflce 12 to permit the discharge of materialtherethrough from the passage 5.

'I'he forward end portions of the air tube 17 110.

in valve sleeve 19 are centered within the nozzle 4 by a spider member20 disposed in the nozzle passage 5. 'I'he opening 18 is sealed againstleakage around the valve sleeve 19 by the gland nut 21 and the customarypacking.

'Ihe rear end of the valve sleeve 19 is fixedly secured to a slidemember 22 that is mounted for sliding movements in a sleeve 23, mountedin the gun body opening 14, and cooperating with the slide member 22 toclose the rear end of said opening. The sleeve 23 is held to its seat inthe forward end of the opening 14 by the plug 15.

A coiled expansion spring 24 is mounted within the sleeve 23 with oneend thrust against the plug 15 and its other end thrust against ashouldered portion of the slide member 22, and acts to Vnormally urgegsaid member and the valve sleeve 19 forward to seating position in thenozzle 4. The forward end of the slide member 22 is annularly recessedaround the valve sleeve to slidingly receive the tubular stem portion 25of a thrust-member 26 which has a transverse opening through its forwardend portion for receiving the cross-pin 27 of the control trigger 28 ofthe gun. A coiled expansion spring 29 is mounted Within the members 22and 25 in opposed end thrust engagement therewith to normally maintainthe thrust member 26 at the limit of its forward movement relative tothe slide 22. The spring 29 is weaker than the spring 24 and thepermissible rearward movement of the thrust-member 26 relative to theslide 22 isonly suiiicient to permit such thrustmember to actuate an airvalve 30 disposed in an air supply passage 31 and open such valve beforethe continued movement of the thrustmember 26, by an operation of thetrigger 28, eiects a rearward movement of the sleeve 22 against thetension of the spring 24 and a consequent retraction o1' the valvesleeve 19 and opening of the material discharge orice 12.

A stem 32 connects the thrust plate 26 to the valve 30 and impartsmovement from one to the other'thereof. 'Ihe valve 30 is disposed with avalve cage 33 and is normally held seated by the action of a spring 34disposed in such cage.

It will be understood that when the gun -is in use, the passage 31 willbe connected to provided in the plug 15 and a portion passing throughthe passage 37, provided in the top portion of the gun body, to the'air.Aspace 10 between the nozzle members 4'and 7.

I t is apparent that to operate thel gun, the operator retracts thetrigger 28, causing rst a movement of the thrust plate 26 relative tothe slide member 22 to effect an initial opening of the air valve 30 andthen, upon a continued rearward movement of the' trigger and thrustplate to effect a rearward movement of the slide member 22 and sleevevalve 19 to open the material discharge orice 12 Without disturbing theposition of the discharge end of the air tu 17 relative to the nozzle.By opening the a' valve before the sleeve valve is moved to open theorifice 12 permits the discharge of air both from the tube 17 and fromthe air discharge orifice 11 in advance of the discharge the breaking upand atomizing of anymaterial discharging from thegun.

By discharging the atomizing air interiorly of the material stream andalso in enveloping relation thereto, a very'eiiicient breaking up andnely atomizing of the material is elected and this manner of dischargingthe air isparticularly important when handling brushing dopes and othermaterials of a more viscous nature than other paints and surface coatingmaterials,

It is sometimes desirable to regulate the pressure of the air streamsdischarging from the tube 17 and from the orifice 11 so that they may beof the same pressure or of different pressures to suit the particularuse. For this purpose, a valve 38 is provided to control the quantity ofair and consequently the pressure of the same passing through the tube17 and a valve 39 is provided in the passage 37 for regulating thequantity and pressure of the air passing therethrough to the orifice 11and also to the supplemental air discharge passages 13.

The valve 38 in the present instance is threaded sage 37 as shown, saidplug being threaded in a top opening provided in the gun body 1.

I wish it understood that my invention is not limited to any specificconstruction, arrangement or form of parts, as it is capable of numerousmodifications and changes without departing from the spirit of theclaims.

Having thus described my invention, whatI claim as new and desire tosecure by Letters Patent is:

1. In a spray gun, a sprayhead having an inner material discharge nozzleand an outer air discharge nozzle, a tube projecting into the innernozzle to cooperate therewith to form a material discharge orice andadapted to have communication with a source of air pressure supply, avalve member slidably mounted on said tube and operable to open andclose said orice, a valve for controlling the supply of air to both saidtube and said air nozzle, and means operable to open both said air valveand said nozzle valve member.

2. In a spray gun, a gun body having an opening in its rear end and aspray head at its forward end, said spray head having an inner materialdischarge nozzle, a bearing sleeve disposed in said opening, a memberclosing the rear end of the opening, a tube projecting from said memberforwardly through said opening and into said nozzle and cooperating withthe latter to form a material discharge orifice, said tube havingcommunication through said member and aA portion of said body with asource of air pressure supply, a normally closed valve in saidcommunication, a valve sleeve slidingly mounted on the tube and havingits v'forward end adapted to enter and close said oriiice and havingitsrear end extending into said opening and having 1a bearing in saidbearing sleeve, means acting on said bearing to normally retain thevalve sleeve in orifice-closing position,'and

control means operable to open the air valve upon an initial movementthereof and upon a continuing movement to retract the valve sleeve fromorifice closing position.

3. In a spray gun, a spray head having an inner material dischargenozzle andan outerair discharge nozzle, a tube projecting into the innernozzle to cooperate therewith to :form a material discharge orice andadapted to have communication with a source of air pressure supply, avalve member slidably mounted on said tube and operable to open andclose said orice, a valve for controlling the supply of air to both saidtube and said air nozzle, means operable to open both said air valve andsaid nozzle valve member, and separate means independently operable toregulate lthe pressure of discharge of air from said tube and airdiscnarge nozzle.

4. In a spray gun, a gun body having a spray head at its forward endwith an inner material discharge nozzle and outer air discharge nozzleand having an opening in its rear end, means removably mounted in saidopening, a tube carried byr and projecting forwardly from said meansinto said material discharge nozzle and cooperating therewith to form amaterial discharge orifice, said tube having communication at the rearof its forward end with a source of air pressure supply, a valve sleevemounted on said tube for movements lengthwise thereof and having itsforward end adapted to enter said orice and to close the same, meansacting on said Valve sleeve to normally retain it in oriceclosingposition, means operable to retract the valve sleeve fromorifice-closing position, a valve operable to control the supply of 'airto both.V

said tube and air nozzle, and separate independently controlled valvesoperable to regulate the air pressure discharging from said tube and airnozzle.

5. In a spray gun, means forming three concentric oriiices, theintermediate orice being for the discharge of a material and havingcommunication with'a source of material supply, and thel other twoorices being for the discharge of air and in communication with an airpressure supply, and means for regulating the volume and pressure of airdischarge from the center orice to effect a greater or less pressure ofdischarge from said center orice than from said outer orifice.

6. In a spray gun, a nozzle having three cona centric discharge orices,the innerand outer orices for air and the intermediate orifice for thematerial being sprayed, said orifices having communication withrespective sources of material and air pressure supplies, and separateindependently regulable valves operable to control the respectivedischarge of air and material from said orices. l

1. In a spray gun, a spray head having a xed inner material dischargenozzle land a fixed outer air discharge nozzle cooperating to form anannular air discharge orifice in outwardly spaced concentric relation tothe material discharge orifice of the inner nozzle, a fixed tubeprojecting into the inner nozzle to cooperate therewith to form anannular material discharge orifice and adapted to have communicationwith a source of air pressure supply, anda control valve member sleevedon said tube for reciprocatory movements relative theretoand adaptedwhen in one position of its movement to seat in said annular materialdischarge orice and close the same.

8. In a spray gun, a spray head having a fixed inner material dischargenozzle and anouter air discharge nozzle cooperating to form anannular'air discharge orifice therebetween, a fixed air discharge tubeprojected through the inner discharge nozzle and cooperating therewithto form an annular air discharge orice, a tubular valve member closelysleevedon said tube for reciprocatory movements longitudinally thereofandhaving its outer end adapted to enter and close the annular materialdischarge orice, manual control means for said valve member, and meansfor controlling the supply of air respectively to said tube and saidouter air discharge orifice. y

ROBERT W. TRACY.

